Parameter defaults: which behaviour? Be precise

[eliegoudout]

Currently, values are looked-up in instance dict and then in class MRO. Furthermore, default values are inferred at class creation from the latest class defining it as parameter and are immutable. For example:

# Currently
from paramclasses import IMPL, MISSING, ParamClass


class A(ParamClass):  # Defines "x" as one of its parameters
    x: int

class B(A):           # Does not define "x" as a parameter
    x = 0

B.x = 1

assert getattr(B, IMPL).default["x"] is MISSING  # Passes
B()                                              # B(x=1)

A.x = 2                                          # Doesn't affect default
assert getattr(A, IMPL).default["x"] is MISSING  # Passes
assert getattr(B, IMPL).default["x"] is MISSING  # Passes

1. Is it ok to bypass classes not defining "x" as a parameter (e.g. B)?
2. Shouldn't we reflect the A.x = 2 change in defaults? I think we should.

For 2., use a (param, owner) approach, similar to protected attributes.

[eliegoudout]

On the other hand, it's kind of weird to consider B().x == 1 as a non-default value, no?